I. Field of the Invention
The present invention relates to apparatus for cutting muntin strips. More specifically, the present invention relates to apparatus for severing and mitering muntin strips and connectors for enabling the assembly thereof.
II. Description of the Prior Art
Traditionally, muntins or muntin strips have been used as decorative dividers or spacers between or outside panes of glass used for windows and doors. The muntins render the panes of glass aesthetically appealing. Because the muntins are frequently utilized between glass panes, they must present a flat mating surface to prevent the glass from seating against them. The flat surface is reasonably easy to sustain if the muntins are all aligned in a single direction. However, it becomes more difficult to sustain the flat mating surface at an intersecting joint of two muntins laid out in different directions or in other directional configurations.
Another common problem is the separation of the muntins which may occur at the intersecting joints over a period of time. This destroys the designs created with the muntins and the aesthetic quality provided to the windows by the placement of the muntins.
Several methods for assembling muntins to provide flat and strong intersecting joints are known. For example, muntin sections have been welded together to create a solid grid-type lattice structure, and then ground at the weld to eliminate rough surfaces caused by the weld. However, the welded strips, although they are structurally solid, create other problems. Glass panes, whether in a window or a door, expand in warm temperatures and contract in cold temperatures. To accommodate for this expansion and contraction, the muntins must be flexible. The welded muntin grids tend to be inflexible, which causes the glass panes to eventually crack. Also, the grinding of the weld does not produce consistently flat surfaces at the weld. This promotes stress on the glass panes. Further, the heat from welding occasionally causes the muntins to warp, which also causes stress on the glass panes.
Thus, other methods and devices have been developed to provide muntin grid assemblies that are reasonably solid and flexible. A typical example of this is the keeper developed by Allmetal, Inc. of Itasca, Ill. The Allmetal keeper is a plastic keeper or connector which is used to join muntin sections wherein the plastic keeper is installed in a first muntin section. Then, second, third, fourth, etc. muntin sections are mounted onto the keepers to form the grid.
An alternate keeper is that developed by Hygrade Metal Moulding Manufacturing Corp., Farmingdale, N.Y. The keeper sold by Hygrade system has a configuration different from that developed by Allmetal but is used and installed in a first muntin section with second, third, fourth, etc. muntin sections being installed thereonto, similarly to that of the Allmetal keeper.
Although the keepers provide structured flexibility, the solidity that is sought and the flexibility in lattice design are limited because of the shape of the joining ends of the muntin sections. The ends of the muntin are commonly square cut, as needed, to mate flush against another muntin. However, problems arise when muntin sections are not shaped to receive a square cut. The square or flush cut has a tendency to rock or separate from a flush fit during both assembly and use, even though the muntin section is seated on a plastic keeper. The rocking may cause bent edges which, if not caught during inspection, may contact the glass, thus, causing stress points on the panes of glass. Also, the joint may come apart during use, destroying the aesthetic appearance of the lattice.
Hygrade Metal, in addition to developing keepers, has attempted to address the above problem by notching muntin sections which are used in crossbar assemblies. The notched muntins are interlaced one on top of the other with the notches facing each other. In most cases, the notches permit the two muntins to merge to the thickness of one muntin. However, if there is no exact merger, the intersecting surfaces are not flat. Again, this provides stress on the glass pane. Also after assembly and in use, the expansion and contraction of the glass and metal due to changes in temperature causes the intersecting muntins to separate and the glass to contact the muntin, thus, creating stress on the glass panes.
It is also noteworthy that the assembly process generally used to assemble the muntins involves cutting the muntin sections with a single stationary blade or cutter which produces a square cut, or by routing. Routing leaves large burrs which present assembly problems if not removed. To obtain an angle cut, the muntin is positioned at a desired angle and then cut by the single blade. The muntin sections are next either punched with a hole or are notched. The punched and notched muntin sections are moved to an assembly station where an assembler assembles the notched pieces and/or inserts keepers in the punched holes and assembles the muntins together.
A single blade or cutter is usually operated by an operator who positions the muntin strips and presents them to the cutter. This operation is slow, time consuming and labor intensive, and it does not assure consistent, high quality parts. Routed muntins, on the other hand, leave burrs which must be ground to secure a good fit. This, again, is time-consuming and labor intensive. Because inconsistency and the other problems tend to result in insulated windows of questionable quality or longevity, an apparatus and method of producing consistent muntin sections and high quality muntin assemblies in a shorter time period and at a reduced cost is highly desirable.